As a DevOps engineer, I want to be able to cancel a PipelineRun that is currently in progress to save computational resources and prevent unnecessary workload from running to completion.

Description

In managing continuous integration and deployment pipelines, there are situations where a PipelineRun needs to be stopped while in progress. This may be necessary to prevent a misconfigured or outdated run from consuming resources, or to free up capacity for higher-priority tasks. By enabling the cancellation of in-progress PipelineRuns, I can conserve resources and reduce system load, improving the efficiency of the pipeline environment.

Acceptance Criterai

1. *PipelineRun Annotation for Resource-Saving Cancellation*:  
   - A new annotation should be introduced in the PipelineRun definition:
     ```yaml
     pipelinesascode.tekton.dev/cancel-in-progress: "true"
     ```
   - When this annotation is applied, the current active PipelineRun will be canceled after it has successfully started, thereby halting resource consumption immediately.

2. *Scope of Cancellation*:  
   - This feature should apply only to PipelineRuns that are actively in progress.
   - Completed or previously canceled PipelineRuns remain unaffected to avoid any unintended disruptions.

3. *Incompatibility with Concurrency Limits*:  
   - To ensure that resource management remains predictable, the `cancel-in-progress` annotation cannot be used in conjunction with concurrency limits, as outlined in repository configurations.

4. *Documentation and Examples for Efficient Resource Use*:  
   - Documentation should include examples to demonstrate how this feature can be used to cancel runs for resource conservation.